Immunolocalization of androgen receptor in the epididymis of rats with dihydrotestosterone deficiency

Dihydrotestosterone (DHT), 5alpha-reduced metabolite of testosterone, is the most potent androgen in the epididymis. The conversion of T into DHT is carried out by 5alpha-reductase. The activity of 5alpha-reductase type 2, preferentially expressed in the epididymis can be inhibited by a finasteride (a steroid-based specific inhibitor of 5alpha-reductase type 2) which results in DHT deficiency. The aim of the study was to examine the morphology of epididymis and the immunolocalization of an androgen receptor (AR) in the initial segment, caput and cauda epididymis of rats treated with finasteride for 56 days. There were no morphological changes in the morphology of epididymal epithelium in the experimental rats. Immunostainable AR was localized in nuclei of epithelial cells, smooth muscle cells and mainly in the cytoplasm of interstitial cells in the epididymis of control rats. In the epididymis of experimental rats, AR immunostaining was noticed mainly in the cytoplasm of epithelial cells and interstitial cells. The single cells of the initial segment epithelium, basal cells and smooth muscle cells of cauda epididymis showed nuclear AR staining. In conclusion, finasteride affected the expression of the AR in the rat epididymis without changing the morphology of epididymal epithelium. Altered AR expression reflected the hormonal status within the epididymis.     

Ecosystem stress and health: an expansion of the conceptual basis

The assessment of the ecosystem health and departures from it requires clarity of what the system, its structure, dynamics, and healthy conditions are. Available definitions provide inadequate tools to acquire this clarity and may lead to arbitrary diagnoses of ecosystem health but such diagnoses can be overturned on a variety of scientific, philosophical, or political grounds.Nested hierarchy of ecosystem structure compounds the difficulty in the assessment of stress and health because both states may occur simultaneously at different hierarchical levels: with stress at one level being a necessary condition of health at another.An approach based on a formal definition of system change is advanced. First, a conceptual model identifies a self-maintaining minimum interactive structure (MIS) at each level of ecosystem organization. Components of MIS are complementary, coordinated, and exchanging information — they are integrated. Function is defined as a contribution of a component to the maintenance of the whole. In this context health is viewed as persistence of the system at a given temporal and spatial scale. Impairment of the function is stress and is contrasted with change of system structure (loss, addition, or replacement of components of MIS) which is disturbance. Stress can be measured directly by changes of function or indirectly by changes in integration. Even though undesirable from the human point of view, a changed system may again be considered healthy.     

Effect of histamine and H1 and H2 receptors antagonists on carbachol-induced wet-dog shakes in rats

Intracerebroventricular administration of carbachol chloride induced a characteristic wet-dog shake response in rats. Histamine did not change the number of wet-dog shakes during a 60 min observation but intensified the number of episodes in the first 30 min of the experiment. Antagonists of H1 (thenalidine and antazoline) and H2 (cimetidine and ranitidine) receptors, attenuated carbachol-induced wet-dog shakes. It may be suggested that inhibition of the central histaminergic structures decreased central cholinergic activity.     

Effects of histamine and H1 and H2-receptor antagonists on wet-dog-shake episodes in rats induced with tranylcypromine and 5-methoxytryptamine

Intraperitoneally administered tranylcypromine and 5-methoxytryptamine induced in rats the so called wet-dogs-shake behaviour. Histamine injected intraventricularly had no effect on the number or episodes of this behaviour during the first 40 minutes of observation. On the other hand, dimaprit in doses of 5 micrograms/rat injected also intraventricularly increased the number of these episodes. Thenalidine and antazoline--antagonists of the H1-receptor, and cimetidine and ranitidine--antagonists of the H2-receptor, decreased the number of these episodes proportionally to the injected dose. Similar effects were obtained after cimetidine injection into the lateral ventricle. In the light of these observations it may be supposed that these antihistaminic agents exert an inhibitory effect not only on the histaminergic system but decrease indirectly also the activity of the serotoninergic system.     

Expression,localization and possible functions of aquaporins 3 and 8 in rat digestive system

Although aquaporins (AQPs) play important roles in transcellular water movement, their precise quantification and localization remains controversial. We investigated expression levels and localizations of AQP3 and AQP8 and their possible functions in the rat digestive system using real-time polymerase chain reactions, western blot analysis and immunohistochemistry. We investigated the expression levels and localizations of AQP3 and AQP8 in esophagus, forestomach, glandular stomach, duodenum, jejunum, ileum, proximal and distal colon, and liver. AQP3 was expressed in the basolateral membranes of stratified epithelia (esophagus and forestomach) and simple columnar epithelia (glandular stomach, ileum, and proximal and distal colon). Expression was particularly abundant in the esophagus, and proximal and distal colon. AQP8 was found in the subapical compartment of columnar epithelial cells of the jejunum, ileum, proximal colon and liver; the most intense staining occurred in the jejunum. Our results suggest that AQP3 and AQP8 play significant roles in intestinal function and/or fluid homeostasis and may be an important subject for future investigation of disorders that involve disruption of intestinal fluid homeostasis, such as inflammatory bowel disease and irritable bowel syndrome.     

The expression of inducible nitric oxide synthase (iNOS) in the testis and epididymis of rats with a dihydrotestosterone (DHT) deficiency

In our previous studies, we showed that a finasteride-induced DHT deficiency may cause changes in the morphology of the seminiferous epithelium without any morphological alteration of the epididymis. In this study, we demonstrated the constitutive immunoexpression of inducible nitric oxide synthase (iNOS) in the testis and epididymis of Wistar rats treated with finasteride for 28 days (the duration of two cycles of the seminiferous epithelium) and 56 days (the duration of one spermatogenesis). We noted that a 56-day finasteride treatment mainly caused a decrease in the level of circulating DHT, as well as a statistically insignificant decrease in the level of T. The hormone deficiency also led to a change in the iNOS immnoexpression in the testis and epididymis of the finasteride-treated rats. In vitro, DHT did not modify NO production by the epithelial cells of the caput epididymis even when stimulated with LPS and IFNγ, but it did give rise to an increase in NO production by the epithelial cells of the cauda epididymis without the stimulation. DHT did not have a statistically significant influence on estradiol production by cultured, LPS- and IFNγ-stimulated epithelial cells from the caput and cauda epididymis. In conclusion, our data clearly indicates that a finasterideinduced DHT deficiency intensifies the constitutive expression of iNOS in most rat testicular and epididymal cells, so it can be expected that the expression of inducible nitric oxide synthase (iNOS) could be regulated by DHT. On the other hand, the profile of the circulating DHT and T levels strongly suggests that the regulation of constitutive iNOS expression is complex and needs more detailed study.     

Towards the proteome of Brassica napus phloem sap

The soluble proteins in sieve tube exudate from Brassica napus plants were systematically analyzed by 1-DE and high-resolution 2-DE, partial amino acid sequence determination by MS/MS, followed by database searches. 140 proteins could be identified by their high similarity to database sequences (135 from 2-DE, 5 additional from 1-DE). Most analyzed spots led to successful protein identifications, demonstrating that Brassica napus, a close relative of Arabidopsis thaliana, is a highly suitable model plant for phloem research. None of the identified proteins was formerly known to be present in Brassica napus phloem, but several proteins have been described in phloem sap of other species. The data, which is discussed with respect to possible physiological importance of the proteins in the phloem, further confirms and substantially extends earlier findings and uncovers the presence of new protein functions in the vascular system. For example, we found several formerly unknown phloem proteins that are potentially involved in signal generation and transport, e.g., proteins mediating calcium and G-protein signaling, a set of RNA-binding proteins, and FLOWERING LOCUS T (FT) and its twin sister that might be key components for the regulation of flowering time.     

Species–area relationships arise from interaction of habitat heterogeneity and species pool

Species–area relationships (SARs) represent a ubiquitous and useful empirical regularity characterizing biodiversity. The rate of species accumulation, captured by the value of the exponent, z, varies substantially and for many reasons. We hypothesized that one of the major contributors to this variation is heterogeneity and its change with scale. To test this hypothesis, we used an array of natural microcosms for which we had invertebrate species composition and physical properties of habitat. Using GIS and cluster analysis, we organized the species data into four sets: communities grouped by spatial proximity in the field, randomly, by similarity of their physical habitat and by dissimilarity of their physical habitat. These groupings produced varying levels of heterogeneity at different scales. We fitted species–area and species–volume relationships to the four groups of communities, and obtained z-values for each group or a portion of the group if the slope of the relationship varied. As predicted, we recovered a number of properties reported by others. More interestingly, we found that small- and large-scale habitat heterogeneity produced scale-dependent z-values while the random grouping of pool habitats produced z-values more robust across scales but also susceptible to initial values of habitat richness. Habitat area affected rate at which species accumulated much less than the mean degree of inter-habitat differences: increasing area that is heterogeneous at broader scales produces higher z-values than increasing an area that shows heterogeneity at small scale only. Our results, while from a microcosm system, rely on logic transferable to larger scale data sets.     

Hymenolepis diminuta: The effects of infection on transepithelial ion transport and tight junctions in rat intestines

In this study, we examine the effect of Hymenolepis diminuta on ion transport in the ileum and on tight junctions in the ileum and colon of rats. We also evaluate the effect of H. diminuta on C-fiber endings in the ileum, the direct habitat of H. diminuta, before and after mechanical stimulation and pharmacological modification by capsaicin (C-fiber irritant).Wistar rats were orally infected with five cysticercoids of H. diminuta. Using a modified Ussing chamber, electrophysiological parameters of the ileum were measured (transepithelial electrical potential difference and transepithelial electrical resistance) as well as the deposition of occludin (a tight junction protein) in the ileum and colon of the rats 8, 16, 25, 35, 40 and 60 days post infection.We observed a significant reduction in transepithelial electrical potential difference in the ileum of rats infected with H. diminuta. In both the ileum and colon of rats infected with H. diminuta we also observed a decrease in occludin deposition, which indicates leakage of tight junctions, correlating with the decrease in transepithelial electrical resistance of these tissues. The application of capsaicin confirmed the hypothesis that H. diminuta in rats affects the C-fiber sensory receptors, causing changes in ion transport in the ileum.The results of the performed electrophysiological and immunohistochemical examinations indicate hymenolepidosis-related changes in the active transport of ions and the passive movement of ions.